The invention relates to a punching tool used to punch holes in sheet metal and in particular tools for punching holes in formed sheet metal ceiling tile grid frame work material. A typical grid frame work for a suspended tile ceiling is formed of sheet metal corner angle sections, U channel sections, and T sections which are interconnected by overlapping them and riveting them together. In order to connect the overlapping sheet metal sections, holes are drilled or otherwise formed through which pop rivets may be inserted. These holes must normally be formed at the installation site because it is not usually possible to predict with certainty the locations at which the sections will overlap.